Photosynthesis

Question 1

Heterotrophic nutrition

Answer 1

They have to get food by eating other things

Question 2

Describe Location and structure of the chloroplast

Answer 2

Location: on the surface of leaves
Structure: contains an inner and outer membrane. Inside of it contains the stroma and thylakoids.

Chloroplast is located in nearly every cell of a plant. It is a double membrane enclosed structure. Cells located in the mesophyll layer of a plant contain the highest number of chloroplasts. Chloroplasts contain a jelly-like substance (stroma) where the Calvin cycle takes place. And also stacks (grana) of membranous sacs (thylakoids) where the light reactions take place.

Question 3

Explain how chloroplast structure relates to its function

Answer 3

Chloroplast structure relates to its function in that idk.
The stacks of thylakoids help to increase the surface area, allowing for more photosynthesis to occur. Having the thylakoids stacked also helps decrease the volume a chloroplast occupies, allowing numerous chloroplasts to be in a cell and also increase photosynthesis. Having all of photosynthesis occur within the same structure increases efficiency. The products of the light reactions do not have to travel to reach the Calvin cycle.

Question 4

Autotrophic nutrition

Answer 4

They make their own food through photosynthesis

Question 5

Summary equation for photosynthesis

Answer 5

6CO2 + 6H2O ——> C6H12O6 + 6O2
Sunlight energy

Where: CO2 = carbon dioxide 
H2O = water
Light energy is required
C6H12O6 = glucose
O2 = oxygen

Question 6

What is the function of the light reactions for photosynthesis

Answer 6

The purpose of the is to convert light energy into chemical energy in the form of ATP and NADPH. ATP and NADPH are energy carriers. They carry energy to the 2nd part of photosynthesis, known as the dark reactions. The light reactions can be split into the following steps:

1) light absorption and splitting of water
2) production of ATP
3) movement of electrons through electron acceptors to power a hydrogen pump
4) re-energizing electrons so they can produce NADPH.

Question 7

Explain the role of redox reactions in photosynthesis

Answer 7

The oxidation of water is linked with the reduction of CO2 through a series of redox reactions in which electrons are passed from one compound to another. This series of reactions constitutes the photosynthetic electron transport chain. The process begins with the absorption of light by protein pigment complexes known as photosystems. Photosystems use absorb light energy to drive redox reactions and thereby set the photosynthetic electron transport chain in motion. In turn, The movement of electrons through this transport chain is used to drive the synthesis of ATP and NADPH. And finally, ATP and NADPH are the energy sources needed to synthesize carbohydrates using CO2. Also,
Loss of e- is oxidation; gain of e- is reduction. Water is oxidized, e- pass thru ETC and transferred to NADP+ which is reduced to NADPH. NADPH enters Calvin cycle where it is oxidized and intermediate sugar is reduced.

Question 8

Describe the wavelike and particle like behaviors of light

Answer 8

Frequency is associated with energy in that the higher the frequency is, the higher the energy is. Frequency is associated with color in that the color is always dependent upon the light’s frequency. Light travels in waves - photosynthetic pigments only absorb certain wavelengths. Light can act like a single particle (photon) which bounces around photosynthetic pigments of light harvesting complexes until it reaches chlorophyll a in the reaction center where the photo excites an e-.

Question 9

Describe the relationship between an action spectrum and an absorption spectrum

Answer 9

The action spectrum is A graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process. The absorption spectrum is The range of a pigment’s ability to absorb various wavelengths of light; also a graph of such a range. The action spectrum shows that the chlorphylls in the absorption spectrum are most important because they correlate closest to the action spectrum. Also absorption spectrum shows the % of light absorbed with respect to the wavelength of light. It is usually shown for each pigment. Action spectrum shows the overall amount of photosynthesis (action) with respect to the wavelength of light. It is the total of all pigments.

Question 10

What is the wavelength of light that is most effective for photosynthesis

Answer 10

400-500 is where photosynthesis occurs the most because the wave lengths are shorter so the energy level is higher.

Question 11

Why are plants different colors in the fall?

Answer 11

The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part of their fall splendor. At the same time other chemical changes may occur, which form additional colors through the development of red anthocyanin pigemnts.

Question 12

Explain what happens when chlorophyll or other accessory pigments absorb photons?

Answer 12

When pigemnts absorb photons they are temporarily excited and pass that photon in to the center - chlorophyll a. Absorb light energy is transferred from one chlorophyll molecule to another until it is finally transferred to the reaction center. When the transfer takes place, the reaction center becomes oxidized in the adjacent electron acceptor molecule is reduced.

Question 13

Explain why absorption spectrum for chlorphylls differs from the action spectrum for photosynthesis.

Answer 13

The absorption spectrum shows each pigment separated. The action spectrum shows the combined effects of all pigments - chlorophyll a, cholophyll b and all the accessories (carotenoids)

Question 14

What wavelength is worst for photosynthesis?

Answer 14

Green because it is reflected.

Question 15

List the components of a photosystem and explain their functions

Answer 15

Within a photosystem there are light harvesting complexes which contain photosynthetic pigments (a, b, accessory) and then in the center is the reaction center where there is a cho,pro hull a molecule which collects the light energy and transfers it to an e-.

Question 16

Difference between P680 and P700

Answer 16

The role of the P680 is to absorb light maximally at 680 nm for the light dependent reactions of photosynthesis. The role of the P700 is to absorb light maximally at 700 nm for the light dependent reactions of photosynthesis to take place

Question 17

Trace electron flow through photosystems II and I

Answer 17

First, e- enter from photolysis. Get excited at PS II, lose energy while returning to ground state in ETC, then get re-excited at PS I and then combine with NADP+ and H+ to form NADPH to be used in the dark reactions.

Question 18

What role does water play in photosynthesis?

Answer 18

Water is used in two ways: 1 way is to build up a proton motive force: having water be split and then also having them be pumped across the membrane.

Question 19

Describe the major consequences of photrespiration

Answer 19

It disrupts the normal Calvin cycle. Instead of combining with a 5C sugar to make 6C sugar, there is still a 5C sugar. This is detrimental to the Calvin cycle because it is difficult to make a complete glucose molecule and still regenerate RuBP.

Question 20

Describe the role of ATP, NADPH, and RuBP in the Calvin cycle

Answer 20

ATP adds a phosphate group to intermediate sugars giving it energy. It is also used to help regenerate RuBP. NADPH is used to transfer energy to the intermediate sugars.

Question 21

Describe what happens to rubisco when the O2 concentration is much higher than CO2.

Answer 21

Rubisco will bind O2 to RUBP instead of CO2 when O2 levels are too high. This is photrespiration.

Question 22

Summarize the carbon fixing reactions of the Calvin cycle and describe changes that occur in the carbon skeleton of the intermediates

Answer 22

CO2 enters to combine with RuBP (a 5C sugar) to make an unstable 6C sugar. That splits into 2-3C sugars. Those sugars get phosphate and energy. One 3C sugar stays behind to form glucose. The other is regenerated into RuBP.

Question 23

What are the products of photosynthesis and where is it used?

Answer 23

Sugar (glucose) where it is used in cell respiration and oxygen where it is used for people to breathe

Question 24

Describe two important photosynthetic adaptations that minimize photorespiration

Answer 24

Plants can close their stomata during the day and only open them at night, at which time they fix CO2 into a 4C intermediate sugar (oxaloacetate). This is only done at night.some plants also have specialized cells for carbon fixation (C4 plants).

Question 25

Describe the fate of photosynthetic products

Answer 25

O2 is what all animals breathe in. It is used in aerobic cellular respiration. Glucose is used by the plant for energy and consumers can eat the plant for energy.

Question 26

Compare and contrast C-4, C-3, and the CAM metabolic pathways of photosynthesis

Answer 26

C3 plants - fix CO2 directly to RuBP with rubisco to make G3P or PGAL.

C4 plants and CAM plants – fix CO2 to PEP with PEP carboxylase to make oxaloacetate (4C) at night. In C4 plants this process happens in the bundle sheath cells. Then when the products of the light reactions are present, both release a CO2 from oxaloacetate to allow Calvin cycle to take place as normal. In C4 plants this happens in the mesophyll cell.